PRB: Grid Behavior Isn't Consistent w/ that of List/Combo Box

• Microsoft Visual FoxPro for Windows, versions 3.0, 3.0b
• Microsoft Visual FoxPro for Macintosh, version 3.0b

SYMPTOMS

Visual FoxPro allows list boxes, combo boxes, and grids within a form to be based on the output of a query (.QPR) file. The list box and combo box controls support a Requery method that causes the query to be updated. The grid does not support a Requery method to update the results of a query. Therefore, if the list box or combo box and the grid are populated with the results of the QPR file, the grid looses its data when the Requery method is used on the list box or combo box.

RESOLUTION

Set the RecordSource of the grid back to itself as shown in the code below:

   Thisform.Grid1.RecordSource = Thisform.Grid1.RecordSource

STATUS

This behavior is by design.

MORE INFORMATION

Steps to Reproduce Behavior

1. Open the C:\Vfp\Samples\Mainsamp\Data\Tastrade.dbc database.

2. Create a new form named Frmmyfrm.

3. Add a list box to the form. Set the following properties in the properties sheet:

         List1.RowSourceType = 4 (QPR)
         List1.RowSource = qryTest.qpr
   

4. Add a grid to the form. Set the following properties in the properties sheet:

         Grid1.RecordSourceType = 3 (QPR)
         Grid1.RecordSource = qryTest.qpr
   

5. Add two command buttons to the form. Set the caption of the first button to "List Requery", and the caption of the second to "Grid RecordSource".

6. Add the following code to the Click event of the List Requery command button:

         Thisform.List1.Requery()
   

7. Add the following code to the Click event of the Grid RecordSource command button:

         Thisform.Grid1.RecordSource = Thisform.Grid1.RecordSource
   

8. Close and save the form. Create a new program file with the following code. Save this file as Qrytest.qpr (be sure to add the .QPR extension) and close the file.

         SELECT contact_name, customer_id FROM customer INTO CURSOR curTest
   

9. Enter the following command in the FoxPro Command window:

          DO FORM frmmyfrm
   

10. Click the List Requery button and note that the data in the grid disappears. Click the Grid RecordSource button and the data reappears.

    NOTE: Do not base your grid on a .QPR file if the data in the grid needs to be modified. Data created with a .QPR file is read-only. Creating a view would be a better alternative if data needs to be modified. This requires setting the RecordSourceType of the grid to "2 - Alias" and the RecordSource to the name of the view. The data in the grid could then be refreshed using the REQUERY() function. This is a Visual FoxPro function that can be issued on a command line by itself. The function should be preceded by an equal sign, as in the following example, to update the view with new data:

           
              =REQUERY()
    
    

REFERENCES

Microsoft Visual FoxPro Developer’s Guide, Chapter 8

For more information on this topic, please see the following article in the Microsoft Knowledge Base:

       
   ARTICLE-ID:  Q140653
   TITLE     :  Cursor-Based Grid Goes Blank If SQL SELECT Resets Cursor

Keywords          : buglist3.00 buglist3.00b FxtoolFormdes VFoxMac vfoxwin kbtool kbbuglist
Version           : 3.0 3.0b
Platform          : MACINTOSH WINDOWS
Issue type        : kbbug